Blade-wheel for centrifugal pumps.



PATENTED SEPT. 24, 1907,

PINEUMAM BLADE WHEEL FOR OENTRIPUGAL PUMPS.

. I mmr mmnrv APPLICATION IILifiD 1330.17.1900.

UNl'llliD ll ltl' llllBERG, GERMANY.

BLADE-WHEEL FOR GENTRIFUGAL PUMP S.

'Spificationi of Letters Patent.

' I mtntsse t2 19o7.

lllpplication filed llecember 17. 1906 Serial No. 343,370.

To all whom. it may concm'n:

Be it knowrithat l. li u'rz Nnunitx a subjoetot' the German Emperor, residing at Nuremberg, Bavaria, Germany, have invented new and useful improverncnts -in Blade-Wheels for Centrifugal Pumps, of

' which the following is a specification. I

The present invention relates to improvements in the whee is of cen- If new, as is almost universally the case, the height of entrance b is greater than the height of exit I) the wheel profile then receiving the form shown in-Figurc 1; it is heretofiire usual. to use two rotary surfaces to bound the wheel profile in the elevation. Alter ascertaining the inner and outer'diulixcter ol' the bladewhcel, the calculated inner and outer heights 01' the channels 1),, and b are drawn in and their ends 0011-. nected by means of suitable curves.

V Fig. is a sectional view of a wheel of ordinary form. Fig.2 is a similar-view of the improved form. Fig. 3 shows in plan the blade channels as usually constructed with'the blades curving outwards.

Inthe'exccution ol the wheel profile wlth'two rothry" surfaces (Ifig. 1), equal heights of the channel will be situated on concentric cinrle s, so that each section a-a, bb, cc, etc., taken at right angles to the direction of flow of water, will contain unequal heights. In consequence, the channels receive a very-disadvantageous form, thealcove-mentioned sections having'h the fact that the sections of the channel must decrease along-as straight a line as possible iron] their entrance to their exit. This rcrpliremcnt cannot however he fulfilled by u channel it' the wheel. profileis bounded by two surfaces converging outwardly on redial lines,

as will be shown by thet'ollowing consideration: in Fig. (i the line a I; (7 ll e represents the middle length. of the channel and above the single points a, I), 1-,11. e the appertaining sectional areas of the channel-are graphically shown. The, dotted line shows the increase of sectional area for the channel represented in Fig. 4.

From this curve it will be seen that the increase of section trom a to b takes'place gradually, and from b to d more quickly. The greatest section is in d, and from (1 to e the sectional area again decreases. Investigations made with various wheel profiles show that the dotted line in Fig. 6 represents.thecharacteristlc curve for the decrease of sectional area of these'ch aifnels. On "the one-hand, the losses due toiriction are increased by this disadvantageous form of the channel section, and on the other hand, more especially in the case of liiglepressure centrifugal pumps with "a very high.

is not uniformly retarded in the channel and in fact towards the eiiit an acceleration again takes-place. The resistance necessary for the passage of theywater through the channels is essentially increased by the unavoidable impulse losses and this may result in the tinned that the disadvantageousforms of the entrance and exit sections make an accurateineasurement of these sections very difficult. 4

The above-mentioned disadvantages are entirely avoided in theprcsent invention. bladeavheel the channelsare so constructed, that their sectional areas at right angles to the flow of the water have an exactly rectangular form, and further, thatthe area oi the individual sections increases or decreases along a perfectly straight line.

The heights of the now rectangular sections a'a, b-b, 'cc etc: (Fig. 3) are now calculated in such a manner that the sectional area. from the entrance to the exit, that is to say, from a to 0, increases along a straight line; In this way a channel is attained, as shown schematic ally in Fig. 5. Fig. 2shows the blade profile along the line A 13 in the plan view. 4 In the heretofore usual tor n -ollconstruction,equal heights of the blades were situated on concentric circles, while in the form chosen equal areas of t-he chnnucls.

' The unbroken line ilrl ig ti'shows the increaseof sectional area in the channel'. In this new form of construotion the ideal increase of section along a straight line hasl ccn attained. This here' described new form of construction offers the following advantages over the heretofore generally used terms: 1.) In consequence of. the rectzniguliu' section oi the channels, the losses through friction are reducedfto a minimum. consmplcnce oi the decrease of section along a. straight line, the transition oi pressure and velocity in the channels will be perfect. l urthcr, this regular transition of pressure Tenn-[res all losses through impulse in the wheel, and ccntriiugul pumps .equippcd with these blade-wheels ure especially rcinurlcihle for their runnumber of revolutions, a regular transition of'the pressure of the water flowing through the channel'will become impossible through the same cause. The velocity total-effective power of the pump being influenced to --a.-gy nsid,eigible degree. And finally, it must'be men- In the new form of.

In th'e plan view the channelsappear as heretofore;

in this invention, equal heights of blades are iou'nd on ning silently and without jolt. These advantages will essentially help to increase the total effective power of a centrifugal pump. Further the rectangular-form oi the entrance and exit sections permit easvand exact measurement, so that the dimensions of-the finished wheel, can be controlled and compared with the results found b v calculation.

The rectangular cross sectional form 01' the passages is secured in the following manner: It will be apparent that where the impeller is constructed of two walls which converge towards each other on' radial lines as this invention the walls of the passages are thickened and the upper and lower walls thereoi are inade'parallel on the inside. Taking -for instance, the first passage crossed by the line AB, it will be seen that the maxij mum space is provided; In the next'passage the walls would be still parallel but would be drawn closer together by a thickening of the metal, as clearly shown in Fig. 2. In other words, instead of converging the walls on radial lines, they are caused to converge towards each other on lines following the lines of flow of the fluid between the partition webs.

What I claim as my invention and desire to secure by Letters Patent is: I

A rotary member for eentrifurzai'pumps comprising side inemhers' connected by spirally arranged webs forming liquid passages. the entrances to said passages being of greater height than the exits and being of rectangular form on sections taken at right angles to the direction of ilow of the water.

in testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses. FRITZ NI'II'MANN.

Witnesses 

